1. Field of the Invention
The present invention relates to an electronic system, and more particularly, to a shared antenna structure for receiving signals corresponding to two distinct frequency bands.
2. Description of the Prior Art
The ultra-high frequency RFID (UHF RFID) wireless communication technique is widely applied to handheld devices and various electronic devices. In general, an ultra-high frequency signal refers to an electromagnetic wave having a frequency of 300 MHz-3 GHz and a wavelength of 10 cm to 1 m, wherein the wireless fidelity (WIFI) and Bluetooth (BT) communication transmissions are common applications. The transmission distance of the BT technique is shorter, but the BT technique is more convenient to be paired with electronic devices under an environment which lacks a wireless network.
The RFID technique is also applied to warehouse management systems, to detect bar codes on merchandise, and thereby manage and check the merchandise. There is a disadvantage, however, that an RFID sensor is usually configured at a fixed location, and therefore the merchandise will be detected only when it is placed on a conveyer belt. Further, under an environment which lacks a wireless network, there is no linking between electronic devices, and therefore the data scanned by the RFID sensor cannot be obtained in real-time.
The NFC technique is a short distance high frequency wireless communication technique that allows electronic equipment to interchange data within 10 cm through non-contacting point-to-point data transmission. The operation of the NFC technique is similar to that of the Taipei metro system easy card and the electronic toll collection (ETC) highway charge system, wherein data transmission can be performed between devices without requiring direct contact. At present, most smart phones are designed to include the NFC communication function, and can be used to interchange data between electronic equipment. Similar to the easy card, a user may thereby trade or pay bills with a smart phone.